Resinous coating compositions



United States PatentO RESINOUS COATING COMPOSITIONS Roget-WI.Christensen, Richland Township, Allegheny (County, Pa., assignor toPittsburgh Plate Glass (Zompany, a corporation of Pennsylvania 'Thisinvention relates to resinous coating compositions having outstandingdurability and chemical resistance, and pertains more specifically tocoating compositions containing an aldehyde modified acrylamideinterpolymer and an epoxidized oil.

In a copending application, Serial No. 490,409, filed February 24, 1955,it is disclosed that usefulresinous materials are readily obtained byreacting an aldehyde, particularly formaldehyde, with an interpolymer ofacrylamide and one or more polymerizable ethylenicallyunsaturatedmonomers. The resulting resins range from soft flexible materials tovery hard solids, depending upon the choice of monomer utilized inpreparing the acrylamide interpolymer which in turn is reacted with thealdehyde. The resins are useful in'coating compositions, givingverytough and mar-resistant ,films which possess excellent chemicalresistance. f

It has now been discovered that outstanding coating compositions can beobtained by, blending the aldehyde modified amide interpolymers with anepoxidized'oiL' The resulting coating compositions form films withfexhyd .as represented by formaldehyde, to give the s'truc turc:

cellent flexibility and durability. Moreover, these im-" provedproperties are obtained Without loss, of anyfof the desirable propertiespossessed by'the'aldehyde modi-f fied' acrylamide interpolymers. Theseproperties render the compositions of this invention particularly usefulas finishes subjected to outdoor exposure, as well asj'for" suchotherapplications as container linings, and the like.-

' As stated hereinabove, acrylamide or other polyme'r-. izable amide ispolymerized with one or more ethylenically unsaturated monomericcompounds, and the result'-; ing interpolymer reacted with an aldehydeto form one. component of the coating compositions of this invention.vThe exact mechanism whereby the acrylamide interpolymers are obtained isnot definitely known, but is believed to begin by the formationinitially of a relatively short. chain soluble interpolymer having anapproximate structure as follows, acrylamide being utilized forillustrative" purposes: a

i NH:

wherein M and n have the significance set forth hereinabove.

In theevent the formaldehyde is utilized in the form of a solution inbutanol or other alkanol, etherification may take place so that at leastsome of the methylol groups in the above structure will be converted togroup of the structure CH O Alkyl the alkyl group being derived from thealkanol utilized. The amount of etherification taking place depends inlarge measure upon the pH of the reaction medium,

As will be seen hereinafter, similar products can also 1 be obtained bypolymerizing methylol acrylamide with one or more other ethylenicallyunsaturated monomersjj- Among the monomers which may be polymerized withacrylamide are included methyl acrylate, ethyl acrylate,

butyl acrylate, isobutyl acrylate, hexyl acrylate, octyl acrylate,styrene, vinyl toluene, 'maleate esters such as dibutyl maleate, acidicmaterials such as acrylic acid,

methacrylic acid, maleic anhydride, vinyl ethers, vinyl ketones, vinylpyridines, allyl acetoacetates, glycidyl acrylates', methacrylamide,'dimethylbenzyl methacrylate; In general, it

durenediol dimethacrylate, and the like. is preferred that the monomerutilized contain a single methyl acrylate, butyl acrylate,

acrylic acid, and monomethyl styrene.

It has'been found that preferred acrylamide interpolymersare obtainedwhen at least two monomeric compounds are 'interpolymei'ized with theacrylamide;

In this manner it is possible to tailor-' the interpolymer to have anydesired degree of hardness or flexibility. For

the hardness of two component interpolymers where one of the monomers isof the type'which forms soft homo polymers, and a small quantity of anacid monomer'such as acrylic acid, methacrylic acid, crotonic acid,maleic' acid, or fumaric acid has been found to be particularly usefulas an internal catalyst in that it imparts to the coating compositiondesirable fast curing properties. In

place of acrylamide, any other polymerizable amide, for I example,methacrylamide or itaconate diamide, may be utilized.

Interpolymers of acrylamide with one or more polymerizable monomers aremost readily prepared by carrying out the polymerization in a solvent inwhich the acryl'- amide, a .white, crystalline solid at roomtemperature,- and the other monomer(s) are soluble, and at refluxtemperatures. Butanol has provento be a satisfactory solvent in mostcases.

with water can also be used advantageously as solvents. Some care mustbe exercised when water is present in the Patented June 14, v 1960Isopropyl alcohol, butyl Cellosolve, and mixtures of butanol or otherlower alkanol,

(iho dla'gitation is also desirable;

system a's'g'ummy' precipitates may result, especially at thehighe'rwater levels; The presence" oflower alcohols or water has been found tomoderate the speed of reaction by' lowering the reflux temperature,Butyl or ethyl ace:

tare; or" other: ester: solvents, andhyd'1'*'c ca 1-bons"'sirchi-asixylene and thelihem'ayalsd'heemployed.

In carrying out the polymerization reaction aper oxygen type catalyst isordinarilylptilized. Useful catalysts for this pnrposeincfludeacetylbe'nzoyl peroxide, hydroxyheptyl peroxide,- methyl ethyl ketoneperoxide, cy-

clohexanone peroxide;'-cyclohexyl rhydroperoxide, f 2,4- dichlorobenzoylperoxide, cumene hydroperoxide, t-butyl hydroperoxide, methyl amylketone peroxide, acetyl peroxide, lauroyl peroxide, benzoyl peroxide,methyl cyclohexyl hydropero'xide; p chlorobenzoyl peroxide; di-t' bntyhperoxide, peracetic acid, t-butyl permaleic acid, di-t-butyldiperphthalateetbutyl perphthalic acid, t-butylperacet'ate,

economical of the: aboveperoxygen compounds are entirely satisfactory inmost instances; for example cume'ne-- hydroperoxide can beusedadvantageously at "higher re flux temperatures, whereasbenzoyl peroxidehas been very eflective at lower reflu'x temperatures. For somepolymerization reactions, mixtures of the above peroxygen compounds' areused; to. secure desired conversions;

' The diazo compounds, such'as pemethoxyphenyl-diazo thioi'(2-naphthyl)ether, may alsoibe usedas -polymeriza 'ti on. catalysts in: the'preparation of acrylarnideinterpolymers; 'Redox.catalystsystenis canalso be employed.

.Tne-quantityofcatalyst employed can bevariedcom;

siderablyyhoweven'in most instances it is desirable:-to

- utilize Iiromaboutxfil percent to 2.0 percent.v If.v high 1viscosities are desired, a low initial-level. of catalysgiol lowedgbythenecessary additions to get 100 percentcon- V versiomis preferablyemployed. For low viscosity-inten-f pplyrners-thegbulk ofLthe-catalystis: added initially and:

later, additions .used only to secure. desiredconversions:

Larger amounts of. catalyst added'tinitially giye lower 1 viseosities.;,

. Since it. is desirablefthat. the interpoly erstiofeacr'y la amidewith. other, ethylenieally unsaturated monomers: be relatively lowin'molecular weight. so that they canz.

be dissolved athiglr solids and low viscosities; ,a chain modifyingagent or chain-terminator is ordinarily; added to; thepolymerization:mixture; The use of a-ploweriala- :kanolsuch asgabutanolor amixt-ureioillbutanol. and water as a solvent, together withhigh.catalyst levels, aids con siderably,-. but inlmosti-nsta-nces it ispreferredeto addpcnam se- Another method for preparing acrylamideinterpolymers-involv'es utilization of blocki'or' graffv techniques?Conventional polymerization procedures, such as that described in theforegoing'paragraph, ordinarily result in a random distribution of thecomponents in the interpolymers.- By "block or graft methods, thecomponent can be introduced intotl'ie composition in regularsequence-ororder,.,each.segment being-ofia certain lengthandperiodicity'. These product'sjcan be made such that the acrylamideportion is infixed positionin the chain, this approach involving thepreparation of segments which react in groups'or react in sites alongapre- 7 formed. backbone from which or to which other segments can begrown or attached. The properties of materials and the 'like: It has"been foundthat two ofthemost prepared by thisarelat-ively new techniqueare known to be quite difierent in many instances from interpolymers inwhich the components are randomlyoriented. By the 7 block or grafmethod, one can prepare, by choice "materials offdifl'er'entsolubility,, solventand flame resistance, adhesion, water solubility,and, in fact, almost any desired property can be ft'a'il'ored into. theinterpolymer. 7

Useful resinousmaterials containing, acryl'amide are obtained byreacting, the interpolynier's. preparedaccording to'the methoddescribedabove with an, aldehyde.

Formaldehyde, in solution in water (formalin) or in a1 lower. alcoholsuch as'butfnol', or a romaldehyde yield ing, substance such asparaformald'ehyde, trioxymethylene, or hexamethylenetetraamine, is,greatly preferred.

However, other aldehydes, preferably containingcnly atomszof carbon,hydrogen,.and. oxygen, and including; acetald'ehyde', butyraldehyde,furfural, and the like beused'. e g

It is'prefe'rred' thatthe' aldehyde be reacted with; an"

interpolymer containingfrom about 5 percent to about 45.jpercentbyWeight of acrylamide, the balance being.

the otherliethylenically' unsaturated memento Ii has been found thatthose interpolym e'r's containingjthe higher levels of. acrylamide withthose monomers which ordinarily' form'hardlhomopolynierggive hard andflexible films;'wh'erea's interpolymers containing lower levels ofacrylar'nide with those monomers whichordinarily, form softliomopolymers tend to be considerably softer. It. more than oneethylenicallynnsaturated monomer is polymerized with acrylamidqthe'proportions 'ofsucli additional monomers utilized. willidepend upon thecharacteristics which such; monomer or monomers. wi1lTirhpart to thefinal interpolymer's. For example,. in some trolledamounts-otchain,modifyingmaterialsa: The mere monomerror. monomer the 7catalyst and 'chainmodifyingagent,. if-any,. in the solvent,anderefluxing. the resulting. solution for a timesufiicient torobtainthe-:desiredmonv'er:

sion. Ordinarily;theipolymerization willshe cornpl'etein aboutilto.16'1h0l1t81' As indicated hereinabove, it may in some instances bedesirable to add only a portion of the catalyst: initially," the:remainder being added in increments as. the polymerization progresses.Externalcooling of the polymerization rnixtu're or 1 very accuratecontrol of 'refliix. conditions areimportantin carrying out' the."polymerization because Ofthei-Veryrapid reaction rate and because: the1 reaction is highly; exothermic; Some 1 control ofthe heat of reactionis. obtained b'yiaddingthe acrylarnide to the, polymerization mixtureincrementally.

ternary interpolymei systems. it may be desirable. tolutiliie about20'percenr by; Weight .of ary1amide,.and40" ercentj eachof'twoadditional monomer's' s'uchas styrene and ,butadiene', ,or, in someinstances, such aswhe'n acrylic acid. or some other 'ethylenicallyunsaturated .acid' is hyde for each amide group in the interpolymer, oras low utiliied' as" an internal catalysfllit' is desirable that the'inte'rpolymer contain about '20 percent acrylamide, a totalv ofabout'72 percent to 79 percent of two additional ethyl enically unsaturatedmonomers. and about 1.0 percent to about 8.0 percent of theunsaturatedacid. The amount ofthe'monomers necessary in anyinterpolymerization reaction can readily be determinedby simpleexperiment.

It is ordinarily preferred to utilize *two equivalents of formaldehydefor each amide group present in the interpolymer, although the amountmay be, in considerable excess'of the amount necessary to, formmethylolflg'roups on the polymer chainr Accordingly, thisflrati'o may-beraised or l6wered=considerablygif desiredc Forexample, the ratio may beas high as three equivalents of form-aide as about two-tenths equivalentot formaldehyde for each amide group in the inter-polymer. A

The'reaction is preferably; carried out in the presence of a mild acidcatalyst such as ni aleic anhydride. Other acid actalysts such as oxalicacid, hydrochloric acid, or

sulfuric acid, may'also be utilized, although there is some possibilityof g'elation occurring'if the catalyst is too strongly acidic. Alkalinecatalysts such as sodium hydroxide, potassium hydroxide,hexamethylenetetraamine, and other basic amines may also be utilized,and, in fact, there is evidence to indicate that the useflof the basiccatalysts tends to give faster curing resin films.

If desired, the catalyst may be dispensed with entirely, although it isdifficult to obtain satisfactory, reaction unless a catalyst isemployed. The quantity of catalyst utilized may be varied widely; forexample, as pointed out hereinabove, the'm'ore acidic the reactionmedium, the greater the amount of etherlfication which will occur if analcohol solution of the aldehyde is utilized. If the aldehyde is notused in the form of an alcoholic solution,

hols include those having a carbon group attached to' it is preferred toutilize from about (1.2 percent to. 1:0 percent by weight of catalyst,based upon the weight of the acrylamide interpolymer' which is" reactedwarms" ald'e hyde. t.

The reaction of the acrylamide interpolymer with the aldehyde can becarried out simply by adding the aldehyde epoxy esters of mixtures inwhich most of the esters and the catalyst (if one is utilized)to-the-pelymerization mixture obtained by polymerizing acrylamide andone or more ethylenically unsaturated monomers and refluxing theresulting mixture for a period of fromabout 3 to 5 hours until a desiredviscosity is obtained. The w st. f c d n at an hammer by electronicdistillation as may a portion of the solvent if desired. In fact,-whenthe aldehyde is utilized in the form of a solution in an alkanol such asbutanol, it is desirablethat approximately half of the butanol bedistilled off'at the end of the reaction period and replaced by anothersolvent such as xylol..- It is desirable that the anal resinousmaterial.hayeasolidscontent.of.about 2Q perceutlo- 70 percent and aGardner-Holdt viscosity of about P to Z.

Similar polymeric materials may also be obtained by first reacting theacrylamide withan aldehyde such as formaldehyde to obtain an 'alkylolacrylamide, for example, methylol acrylamide, and then polymerizing themethylol acrylamide with one or more of the ethyleni cally unsaturatedmonomeric materials disclosed hereinabove. The polymerization utilizingmethylol acrylamide is carried out in substantially the same manner aswhen acrylamide is interpolymerized with one or more monomers.

Regardless ofthe method by which the resinous material is obtained, theproducts which are blended with epoxidized oils in accordance withthis,invention will contain in the polymer chainrecurrent groups having, t e.structure wherein R is a lower aliphatic, hydrocarbon radical, that is,the radical derived by removing acrylamide from a loweraliphaticaldehyde; for example, if formaldehyde is utilized'the radical Rrepresents a methylene group (-CH When an alcoholic solution of the aidehyde, for example, a butanol solution. of formaldehyde is employed,.etherification may take place and at least a portion of the alcohol-isreacted into the polymer chain so that at least some of the radicals R;will represent a lower alkyl radical such as butyl, or in other words, amixture of hydrogen and butyl radicals. When the aldehydeisutilizedalone, that is, not in an alcohol solu' tion, the radical Rwill, fo course, represent hydrogen. The free valence's may be satisfiedwith either hydrogen or hydrocarbon, depending on the amide which isutilized.

epoxidized oil pla'st'icizing agents employed may 75 xylol the hydroxylgroup, particularly monohydric aliphatic alcohols such as methyl, ethyl,propyl, or butyl alcohols;

polyhydric alcohols such as the glycols, diethylene glycol and the like;glycerols and polyglycerols, and the like. The alcohols utilized foresterification also include aro- "matic alcohols, and aralkyla1coho1s'su'ch'as1ben2y1 alco hol, and cycloaliphatic alcohols such ascyclohexanol. The epoxidized oil may contain quantities of esters fleeof epoxy groups; however, itis preferred to employ pure present have oneor more epoxide groups in each molecule. Among the epoxidized oils, orepoxy fatty esters which may be admixed with the aldehyde modifiedacrylamide interpolymers in accordance with invention are included thefollowing:

Other materials which may be utilized include epoxidized alkyd resins,epoxidized oils of higher polyols and fatty acids, for example, anepoxidized oil obtained by epoxidiz-- ing an ester of tall oil acids andpentaerythritol, and the like. Allof the epoxy fattyacid estersdisclosed. hereinabove, as well as others, are readily prepared, forexample, by the methods disclosed in US. Patent- 2,458,484. v f Thequantity of fatty acid epoxide ester which is blended with an aldehydemodified aerylami de1inter polymer to form the resinous portion of thecoating compositions of this invention may be varied 'consider-: ably.For example, amounts as low as about 5 percentby weight give enhancedproperties to the coating comg'.

positions, and amounts as high as about 50 percent or' more of the fattyacid epoxide ester may be employed. Preferably, the epoxide ester isutilized in an amount of about 10 percent to 30 percent by weight of theacrylamide containing interpolymer.

' No special expedients are necessary in formulating the coatingcompositions of this invention. For example, they may be prepared simplyby admixing a solution of the aldehyde modified acrylamide interpolymerwith,a solution of the fatty acid epoxide ester. No heating is requiredas the components may be blertdedflreadilyjn the cold state. Solventsutilized are likewise not critical and any solvent'or solvent systemwhich will dissolve, the particular acrylamide interpolymer and epoxideester may be employed. Since the acrylamide interpolymer is ordinarilyprepared in a butanol solution, butanol is pointed out hereinabove, itis desirable to replace aboutone half of the butanol with anothersolventsuchas';

"Pigments such as titanium, dioxide}. carboniblack; and

the may be added to the coating compositions to form any desired color.Other ingredients normally foundiin coating compositions, such asgermicides, fillers,

' V driers,--silicones, and the like may also be added. It isa'lsopossible to include in the coating compositions of this inventionother resinous materials, such-as vinyl resins, alkyd resins, amineresins, or the like. such following table wherein, the. letters have thefollowin;

1 Bomb. I

resins are preferably utilized in minor amounts although largerquantities may also be employedf 1 7 V p 7 When an internal catalystsuehas acry'iicacid; methno additional catalyst is needed to promote thecure of the obtained tfiio'rn coating compositions disclosed lierein-However, inthe'event the interpolymer doesnot contain an internal"catalyst, if is desirable to add "an Suitalile catalysts for thispurpose includ'feeitrief acid, .t artaric acid; and phosphoric" acid,'as we'll as latent catalysts, that is, materials-which decomposeinto-acidic; 7 materials when heated.

' Example I 7 Example 11 Example III Example IV Example V Example VI;

15% Jidryla'rfildea Arylamitle: 15%Acrylamlde: 20% Acrylamide: 20%Acrylamide: 20% Aerylamidez (A) Methyl (A) 20%'l\L'ethyl (A) 25%Styrene; (A) Styrene; (A) ,40% Styrene; (A 80%,Vinyl Methaorylate;Methacrylate; (B) Ethyl (B) 40% Buta- 40% Buta- Toluene (B) 60%E$hyl"(B) 60% Ethyl Acrylate- (liens I diene- Aerylate Acrylats PolymerizationCharge and Prooedure:

Acrylamlde fl nn, "par 3 160 160, 250 '15 .320 32.0 1.000

p 12; 320 320 ....,i 90.80 16.0 B 16.0 B 90-.8 A M, v t a an 908 F 84) E3'0 E ,t..-

. 500 and a 1 m 7 r5 r 51, 51.5 25.1 25 1 49.1 Viscosity (Gardner) Z3Z5-Z6 -Z Formaldehyde Condensate: v v

Butanol Solutions of Formalde- I V V w t hyde 6. 3,4 V. 84-6 6.34' 339'389: V 76/35lpartresln" Maleie'Anhydrlde do- 86,3 1.0 30.13 4:15; 1.15.3V 1.10; 'Reflux Time.;. ..hours. 3' V 34 f 3 4 4 16 Iinel Produet: V r 7Percent Solids 60 1 48. 95 50.5 49A 49 4 41213. Viscosity (Gardne Y I VV U-V' Z o Z V V X-Y Color (Gardner), v l 3-4- vEach otftheinterpolymers prepared according "to foregoing examples when blendedwith fatty acid epoxide estersv form coating compositionsrwhichgiveclear, hard acrylic. acid, or the like is present in the interpolymer;40 films having excellent flexibility and outstanding durabilityonoutdoorv exposure.

' Example Vll 'Eighty five parts ofvinyl toluene, 15 parts ofacrylacidic-material shortly before the" composition is to b mide, 1.part of cumene hydroperoxide and 1 part of tertiary dodecyl mercaptan'were refluxcdfor 2 hours and Refluxing was continued for a. furtherperiod of? 2 hours;

The product was then admixed with a solution compris The followingexamples illnstratein detail'the-prepar ing 2.0 moles of formaldehyde(40 percent solution in 7 tion of theresi-nous materials'fljy thereactiomofinter polymers of acrylamide with ethylenically unsaturatedmonomers, and an aldehyde, and theuse" of such ma 1 te'rials incompositionswith fatty aeid epoxidelestersn butanol) and /3 partof'maleic anhydride added. The resulting mixture was thenrefluxed for 3hours after which the butyl alcohol wasdistilled to provide a producthaving the following properties:

Tfieexamples are not intended to limit the inventi'on, Percent solidshowever; for there are, of course, numerous possible variations "andmodifications;

Examples I to VI These.examplcsiillustrate the. preparation oi aldehydeso modified acrylamide; interpolymers which can be blended, with] fattyacid epoxide, esters to.- form the coating compositions of thisinvention. .The polymerization in each s enample was carr'iedout bymixing the polymerizable.

components with a chain transfer agent (except in Ex;

amplef I where nonerwas utilized) in a solvent such;

'asfbutanolor xylene, and addin a polymerization cat-.,

i'y r, either initially or in increments throughout the polymerization;reaction. The polymerization mixture was' ihen refluxed-(in a bomb whenrbutadiene -lfl was monomer) or a period; of time sufiicient to; obtainii -conversion of substantially 100 percentQ' The polymer-r'zationcharge; refliiitime, interpolymer properties formaldehyde? condensationprocedure; and the properties 7 The resin thus prepared was reduced to.4 5 perc"ent solids in a mixturefoi butanol, mineral .SPirQitspirdjisophorone. Portions thereof were then drawn downon electrolytic tinpjlatewith a 0.014 inch 'drawb'ar andthe resulting films" baked at 3'75- F.for 10 minutes? Can occlirredi V 7 Exar tple' VIII 'Examp'levllisrepeated except that'SS' parts opt-styrene was substituted for the partsoivinyl tolu ne;

'An epoxidized oil bearing the trade name Admex 71.0

was then admixed in varying amounts'with the formal dehyc'le' modifiedacrylamidesinterpolymer to. form clear 0f the resinous CondensationP1130 are r por d T e 2 5 coating compositions: Admex 7l0is'understoodto be an ends were made from the panelsand'processed 'inwater at 250 F." for 60' minutes; No blushing} or popping it isepoxidized oil obtained by treating soybean oil with per- R acetic acid.The epoxidized oil has the following properties:

Acid number 1.0.

Color (Gardner) 1-2.

Viscosity at 25 C. 3.3 stokes.

Specific gravity at 25 C. 0.9903.

Weight per gallon (pounds) 8.24.

Refractive index 1.47142.

Average molecular weight 937.

Volume resistivity at 25 C.:

Dry 15x10" ohm cm. After immersion 0.5)( ohm cm.

The compositions were then spread onto steel plate and 15 baked atvarying temperatures. The quantity of formaldehyde modified acrylamideinterpolymer utilized, the quantity of epoxidized oil utilized, thebaking temperatnre and time, solution appearance, film appearance,

ported in the following table:

wherein R is a member of the class consisting of hydrogen, furyl and asaturated lower aliphatic hydrocarbon radical and R is a member of theclass consisting of hydrogen and lower alkyl radicals, said ester beingpresent in an amount of from about 5 to about 50 percent by weight basedon the weight of the resinous components 10 of said composition.

2. The heat hardenable resinous composition of claim 1, wherein saidester is an ester of an epoxy fatty acid containing from about 8 to 22carbon atoms and said ester contains only atoms of carbon, hydrogen andoxygen.

3. The heat hardenable resinous composition of claim 2, wherein R and Rare each hydrogen.

4. A heat hardenable resinous composition comprising an ester of anepoxy fatty acid containing at least 8 carbon "Sward hardness, impactresistance and flexibility are reatoms, said ester containing only atomsof carbon, hy-

drogen and oxygen, and a monoaldehyde-substituted in Percent Percent 30minute Impact reacrylamide epoxidized baking Solution Film appearanceSwat-d slstance Percent interoil temperaappearance hardness (inches/flexibility polymer ture, F. pound) 1 Catalyst phosphoric acid utilizedin an amount of 0.5 percent based on solids.

Example IX A formaldehyde modified acrylamide-styrene interpolymer (15percent acrylamide-85 percent styrene) was admixed with Admex 710 in aproportion of 85 percent of the interpolymer and 25 percent of theepoxidized oil and clear films thereof were sprayed onto Bonderitesteel, one half of the panel being primed and the other unprimed. Allwere baked for minutes at 300 F. and the films exposed to salt air inFlorida for 9 months. On examination after the exposure period the filmsshowed excellent durability with only slight loss in gloss and some veryminor rust spotting. On the other hand, a film of the acrylamideinterpolymer which was not blended with an epoxidized oil showed muchloss of gloss and poor durability in general with severe erosion andpoor color retention.

Obviously, a great many other aldehyde modified acrylamide interpolymersmay be utilized in place of those specified in the examples. Similarlyother epoxidized oils or epoxy fatty esters selected from thosedisclosed hereinabove may be substituted for the epoxy fatty esters ofthe examples. Modifications in the coating compositions may also bemade; for example, pigments other than titanium dioxide may be utilizedas may difierent solvent systems.

Thus, while specific examples of the invention have been set forthhereinabove, it is not intended that the invention be limited solelythereto, but to include all of the variations and modifications fallingwithin the scope of the appended claims.

I claim:

1. A heat hardenable resinous composition comprising an ester of anepoxy fatty acid containing at least 8 carbon atoms, said estercontaining only atoms of carbon, hydrogen and oxygen, and aninterpolymer of an amide selected from the group consisting ofacrylamide, methacrylamide and itaconic diamide and at least one othermonomer containing a C=CH group, said interpolymer containing from about5 to 45 percent by weight of said amide in polymerized form based on thetotal weight of said interpolymer and being characterized by havingamido hydrogen atoms replaced by the structure terpolymer of acrylamideand at least one other monomer containing a C=CH group, saidinterpolymer containing from about 5 to 45 percent by weight ofacrylamide in polymerized form based on the total weight of saidinterpolymer, said monoaldehyde containing only atoms of carbon,hydrogen and oxygen and from 1 to 5 carbon atoms, said ester beingpresent in an amount of from about 5 to about 50 percent by weight basedon the total weight of the resinous components of said composition.

5. The heat hardenable resinous composition of claim 4 wherein themonoaldehyde is formaldehyde and is present in an amount of from about0.2 to 3 equivalents for each amide group of said acrylamideinterpolymer, and said ester is an ester of an epoxy fatty acidcontaining from about 8 to 22 carbon atoms, said ester containing onlyatoms of carbon, hydrogen and oxygen.

, 6. A heat hardenable resinous composition comprising an ester of anepoxy fatty acid containing from 8 to 22 carbon atoms, said estercontaining only atoms of carbon, hydrogen and oxygen, and aninterpolymer of acrylamide and styrene, said interpolymer containingfrom about 5 to 45 percent by weight of acrylamide in polymerized formbased on the total weight of said interpolymer, said interpolymer havingbeen reacted with an amount of formaldehyde of from 0.2 to 3 equivalentsof formaldeoo hyde for each amide group of said interpolymer, said esterbeing present in an amount of from about 10 to 30 percent by weightbased on the weight of the resinous components of said composition.

7. An article having a metallic surface having, as a coating thereon, aheat hardened film of the resinous composition of claim 1.

References Cited in the file of this patent UNITED STATES PATENTS

1. A HEAT HARDENABLE RESINOUS COMPOSITION COMPRISING AN ESTER OF ANEPOXY FATTY ACID CONTAINING AT LEAST 8 CARBON ATOMS, SAID ESTERCONTAINING ONLY ATOMS OF CARBON, HYDROGEN AND OXYGEN, AND ANINTERPOLYMER OF AN AMIDE SELECTED FROM THE GROUP CONSISTING OFACRYLAMIDE, METHACRYLAMIDE AND ITACONIC DIAMIDE AND AT LEAST ONE OTHERMONOMER CONTAINING A >C=CH2 GROUP, SAID INTERPOLYMER CONTAINING FROMABOUT 5 TO 45 PERCENT BY WEIGHT OF SAID AMIDE IN POLYMERIZED FORM BASEDON THE TOTAL WEIGHT OF SAID INTERPOLYMER AND BEING CHARACTERIZED BYHAVING AMIDO HYDROGEN ATOMS REPLACED BY THE STRUCTURE